mixer with 5 tubes

[hooman]

hi
this is my first post .  analog tube mixer Simple, But Not Easy .  my plane  :4 mono  input just control by  one switch.2 mono  input  with mix  pot  and  pan control . 3 mono  input with  mix pot .and  2 stereo input  with  mix pot .used  1 x 12au7 in mono  section for best stereo  signal . .2x12av7 for  EQ amp  and main  process  of  stereo  signal .2x12fq7 for out put in low impedance.

 

[hooman]

.for  best result in hum  i used  dc  for  all  filaments .  ac  transformer  fixed in back of  box .

 

[hooman]

i  don't  use  audio  transformer  in  this project . when i start  to  build  this mixer  first searching  for  good circuit with  no transformer  in input and output and  simple  in EQ.

 

[hooman]

test  10 khz  in  sum  mixer ....... EQ  circuit  can check  by osiloscop  for best result .

 

[hooman]

EQ  circuit  can  change  frequency  of  all in put  in main mixer  amp .there is 4 separate  sections by  keys and pots for  control frequency  , user    can  cancel eq  circuit  and signal  receive to output without any  change .
this is very  simple  . 

 

[hooman]

  we can meet  world class engineers in mixers  and analog record gear  like  mr Ian Thompson-Bell  in this nice  place . so i am waiting for  good advise  before  complete my  project .

 

[hooman]

20 hz to 45  khz  in stereo and  30 t0 25 khz in mono  ,,,,,,,,,,  i used  small tube amp pcl86  for monitoring . i  found this kind of tube mixer in internet .never  found  circuit diagram ....  just  2  low resolution inside pictures  of new  made mixer .it was not  so easy to understand  which topology  that designer used  for eq ?

 

[ruffrecords]

I think you have done very well to extract all this information from a couple of pictures. Well done.

Cheers

Ian

 

[hooman]

I think you have done very well to extract all this information from a couple of pictures. Well done.

Cheers

Ian

Thank you for showing  the  art of    tubes  in audio    . This is most  important....when i saw your  pages in inter net  i  understand  why  analog tube mixer is alive?......why modern  circuit  with  vacuum tubes  can  improve quality  in  studio ...?
simple but  not so easy . in my country we  don't have  easy  access to    all parts  like other in world.   but  love  the tubes  magic .10 years before  i started to  buy  tubes . i have  more audio tubes  ..some times  buy  audio transformer  for  tube mic preamp.
again thanks  to you 

 

[hooman]

i was member of  famous  diy  forums  sins 2008 ...but to day find this place with professional peoples    this  forum is very strong but  very  friendly and easy  to use for members and visitors!!!!!!!!!!! .before our king  buy best of any product  for  us .

so  to day i have more than 1000 of tubes liks rca 2a3 .....u52 from uk .....6550 tung sol  ..12ax7 tele . 211 of usa ......gz32 mullard ...and ...and
i have experience with  tubes in  high gain circuit in guitar amp ....  tube mic  preamps ...hifi amps ....
i am working in  panasonic  service as technical manager for 10 years .and  10 years  in sony as technical center in audio .
noting  dangerous for other people .

 

[hooman]

most important  point for tube mixer  project  is hum  :  in project s  without pcb  ... can  test  and find best grounds point , for  removing hum .i used  amps with  gain to hearing hum  when all pots in max  position . :

 

[hooman]

2x12fq7  in parallel  triodes for  low out put impedance.nice tubes  good sound.

 

[hooman]

    pair    of 12av7 used in hart of mixer.

 

[hooman]

 

[hooman]

this analog tube mixer  is simple but very useful and sound is amazing .
no inexpensive audio transformers ...good  eq circuit.....harmonic
The EQ section :low  boost- hi  boost -low  cut -
hi  cut.
The harmonic  control increases gain and harmonic
tube  sound ... for  tube lovers .
12fq7  good for out put ....12av7  has enough  gain for  eq circuit ....12au7  good for mono mixing in stereo mixer . 

 

[hooman]

for panning  i used  mn pots .

 

[ruffrecords]

What are mn pots?

Cheers

Ian

 

[hooman]

What are mn pots?

Cheers

Ian

hi...  i am  sorry.... :-[ mn taper pots  ....not brand .

 

[ruffrecords]

hi...  i am  sorry.... :-[ mn taper pots  ....not brand .

Cool never heard of Bourns MN taper before. Thanks for that.

Cheers

Ian

 

[Phrazemaster]

Dude! You’re a force of nature! Fabulous work!!!

Welcome (back?) to the forum!

Mike